code: def merge_label(self):
      label_raw = ""
      label_file_regex = os.path.join(
          self.output_dir, "label", "*_label.txt"
      )
      label_file_list = glob.glob(label_file_regex)
      for label_file_i in label_file_list:
          with open(label_file_i, "r") as f:
              label_raw += f.read()
      label_file_path = os.path.join(self.output_dir, "label.txt")
      with open(label_file_path, "w") as f:
          f.write(label_raw)
  
file_path: PaddleOCR/StyleText/engine/writers.py
imports: import os
  import cv2
  import glob
  from utils.logging import get_logger
label_desc: Use image node_id 4 for calling the SimpleWriter obj's underlying member method code with example usage: obj.merge_label() without return types